Display device and method of manufacturing display device

ABSTRACT

A display device according to the invention includes: a first substrate that includes a flexible substrate, is segmented into a display area and a non-display area outside the display area, and includes a thin film transistor and an electroluminescent light-emitting element formed on the display area of the flexible substrate; and an IC chip that is bonded on the non-display area of the first substrate via an anisotropic conductive film, wherein the first substrate includes, between the flexible substrate and the anisotropic conductive film, at least one or more support layers whose plan view shape is larger than that of the IC chip and whose hardness is higher than that of the flexible substrate, and the IC chip is located inside the at least one or more support layers in a plan view.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2013-207137 filed on Oct. 2, 2013, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and a method ofmanufacturing a display device.

2. Description of the Prior Art

In recent years, flexible display devices including a bendable substratehave been developed. As a substrate of the display device, a TFT (thinfilm transistor) substrate including thin film transistors formed on aflexible resin substrate, or a color filter substrate including colorfilters formed on a resin substrate is used. In the TFT substrate,circuits are formed in a display area of the TFT substrate, whileterminals to connect an external connection apparatus with the circuitsare formed in a non-display area outside the display area.

As the TFT substrate of the display device, the publication of JapanesePatent No. 3850915 discloses a technology for a TFT substrate includinga polyimide film on which an IC chip is mounted has been disclosed. TheTFT substrate is flexible, and solder is formed along the perimeter of acircuit component mounted on the polyimide film.

SUMMARY OF THE INVENTION

In general, a method of manufacturing the TFT substrate in the displaydevice includes a step of sequentially forming a flexible resinsubstrate and a thin film transistor on a glass substrate, a step ofpressure bonding an IC chip on the resin substrate via an anisotropicconductive film, and a step of separating the resin substrate from theglass substrate.

The hardness of the resin substrate is lower than that of the glasssubstrate. Therefore, in the manufacturing method, pressure acting fromthe IC chip on the anisotropic conductive film is absorbed by the resinsubstrate when pressure bonding the IC chip on the resin substrate. Forthis reason, there is a risk that electrical conduction between the ICchip and the thin film transistor via the anisotropic conductive filmmay become unstable.

The invention has been made in view of the circumstances describedabove, and it is an object of the invention to realize an improvement inthe reliability of a display device.

(1) A display device according to an aspect of the invention includes: afirst substrate that includes a flexible substrate, is segmented into adisplay area and a non-display area outside the display area, andincludes a thin film transistor and a display element formed on thedisplay area of the flexible substrate; a second substrate that isarranged so as to face an upper surface of the display area of the firstsubstrate; and an IC chip that is bonded on the non-display area of thefirst substrate, wherein the first substrate includes, between theflexible substrate and the IC chip, at least one or more support layerswhose plan view shape is larger than that of the IC chip and whosehardness is higher than that of the flexible substrate, and the IC chipis located inside an area where the at least one or more support layersare provided in a plan view.

(2) According to the display device according to the aspect of theinvention, in (1), the at least one or more support layers may belocated outside the display area in the plan view.

(3) According to the display device according to the aspect of theinvention, in (1), one of the at least one or more support layers may bea metal support layer formed of metal.

(4) According to the display device according to the aspect of theinvention, in (3), the metal support layer may be formed in the samelayer as a wiring of the thin film transistor.

(5) According to the display device according to the aspect of theinvention, in (1), one of the at least one or more support layers may bean insulating support layer formed of an insulating material.

(6) According to the display device according to the aspect of theinvention, in (1), one of the at least one or more support layers may beformed of polysilicon.

(7) According to the display device according to the aspect of theinvention, in (1), the at least one or more support layers may includean insulating support layer formed of an insulating material and a metalsupport layer formed of metal, the insulating support layer may beformed closer to the side of the flexible substrate than the metalsupport layer, and an insulating film may be formed between theinsulating support layer and the metal support layer.

(8) According to the display device according to the aspect of theinvention, in (7), the insulating film formed in the same layer as agate insulating film of the thin film transistor.

(9) A method of manufacturing a display device according to anotheraspect of the invention includes the steps of: forming, on a basicsubstrate, a flexible substrate that is segmented into a display areaand a non-display area outside the display area; forming, on theflexible substrate, at least one or more support layers whose hardnessis higher than that of the flexible substrate; forming, on the displayarea of the flexible substrate, a thin film transistor and a displayelement; arranging a counter substrate so as to face the display area;bonding, on the non-display area of the at least one or more supportlayers, an IC chip whose plan view shape is smaller than that of the atleast one or more support layers so as to be located inside an areawhere the at least one or more support layers are provided in a planview; and separating the flexible substrate from the basic substrate.

(10) According to the method of manufacturing a display device accordingto the aspect of the invention, in (9), in the step of forming the atleast one or more support layers, the at least one or more supportlayers may be formed so as to be located outside the display area in theplan view.

(11) According to the method of manufacturing a display device accordingto the aspect of the invention, in (9), a metal support layer as one ofthe at least one or more support layers may be formed of metal.

(12) According to the method of manufacturing a display device accordingto the aspect of the invention, in (11), the metal support layer may beformed in the same layer as a wiring of the thin film transistor.

(13) According to the method of manufacturing a display device accordingto the aspect of the invention, in (9), an insulating support layer asone of the at least one or more support layers may be formed ofpolysilicon.

(14) According to the method of manufacturing a display device accordingto the aspect of the invention, in (9), the at least one or more supportlayers may include an insulating support layer formed of an insulatingmaterial and a metal support layer formed of metal, the insulatingsupport layer may be formed closer to the side of the flexible substratethan the metal support layer, and an insulating film may be formedbetween the insulating support layer and the metal support layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a display device according to anembodiment of the invention.

FIG. 2 is a schematic cross-sectional view of the display device shownin FIG. 1 along the cut line II-II.

FIG. 3 is a schematic cross-sectional view of the display device shownin FIG. 1 along the cut line III-III.

FIG. 4 is a schematic cross-sectional view showing a modified example ofthe display device shown in FIG. 1 in the same view as FIG. 3.

FIG. 5 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing a method ofmanufacturing a display device according to an embodiment of theinvention.

FIG. 6 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 7 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 8 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 9 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 10 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 11 is a schematic cross-sectional view showing the display deviceshown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

FIG. 12 is a schematic cross-sectional view showing the display deviceshown in FIG. 4 in the same view as FIG. 3, showing the method ofmanufacturing the display device according to the embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a display device according to an embodiment of theinvention will be described using a display device 1 as an example basedon the drawings. In the drawings referred to in the followingdescription, a feature portion is shown in an enlarged manner in somecases for convenience sake for easy understanding of the feature.Therefore, the dimension ratio or the like of each component is notalways the same as the actual component. Moreover, a material or thelike illustrated in the following description is shown by way ofexample. Therefore, each component may be formed of a different materialor the like from the illustrated one, and the invention can beimplemented by changing the material or the like within a range notchanging the gist of the invention.

FIG. 1 is a schematic plan view of the display device 1 according to theembodiment of the invention. FIG. 2 is a schematic cross-sectional viewof the display device 1 shown in FIG. 1 along the cut line II-II. Thedisplay device 1 includes a first substrate 10 in which thin filmtransistors 11 are formed, a second substrate 50 arranged to face adisplay area D of the first substrate 10, and an IC chip (IntegratedCircuit) 3 arranged on a non-display area E of the first substrate 10.

The first substrate 10 is a member on which the second substrate 50 isarranged to face an upper surface 10 a of the display area D of thefirst substrate 10. The first substrate 10 is segmented into the displayarea D and the non-display area E outside the display area D. In thedisplay area D, an undercoat layer 6, a circuit layer 12 including thethin film transistors 11, a planarization film 13, organicelectroluminescent light-emitting elements 30 as display elements, and asealing film 40 are stacked on a flexible substrate 5 formed of, forexample, resin.

The flexible substrate 5 is a flexible substrate that functions as abase material of the first substrate 10. The flexible substrate isformed of resin such as, for example, polyimide. However, the flexiblesubstrate may be formed of other materials as long as the material hasflexibility to allow the first substrate 10 to bend.

An upper surface of the flexible substrate 5 may be covered with theundercoat layer 6. The undercoat layer 6 is a layer formed of aninsulating material to maintain insulation between the flexiblesubstrate 5 and the thin film transistors 11. The undercoat layer 6 isformed of, for example, SiO₂, but may be formed of other materials ormay have a configuration of two or more layers stacked on each other.

The circuit layer 12 is a layer in which the thin film transistors 11, apassivation film 11 f, and electric wirings (not shown) are formed. Thecircuit layer 12 is formed to drive the organic electroluminescentlight-emitting elements 30.

The thin film transistor 11 is provided in each of pixels P on theflexible substrate 5. Specifically, for example, the thin filmtransistor 11 is composed of a polysilicon semiconductor layer 11 a, agate insulating layer (first insulating film) 11 b, a gate electrode(wiring) 11 c formed of, for example, MoW (molybdenum tungsten), asecond insulating film 11 d, and a source-drain electrode 11 e formedof, for example, Al (aluminum). The material of the gate electrode 11 cor the source-drain electrode 11 e is not limited to the exampledescribed above, and other metal materials or alloys may be used.

Moreover, the thin film transistor 11 is covered with the passivationfilm (third insulating film) 11 f. The passivation film 11 f is formedto protect the thin film transistor 11 and maintain insulation betweenthe thin film transistor 11 and the organic electroluminescentlight-emitting element 30.

The planarization film 13 is a layer formed of an insulating materialsuch as, for example, SiO₂, SiN, acrylic resin, or polyimide, and isformed so as to cover the circuit layer 12. Since the planarization film13 is formed between the flexible substrate 5 and the organicelectroluminescent light-emitting elements 30, the thin film transistors11 adjacent to each other or the thin film transistor 11 and the organicelectroluminescent light-emitting element 30 are electrically insulatedfrom each other.

Moreover, contact holes 32 a each of which electrically connects thethin film transistor 11 with the organic electroluminescentlight-emitting element 30 are formed in the planarization film 13.

A reflection film 31 may be formed in an area corresponding to each ofthe pixels P on the planarization film 13. The reflection film 31 is afilm to reflect light emitted from the organic electroluminescentlight-emitting element 30 toward the second substrate 50 side. Thereflection film preferably has a higher optical reflectance, and a metalfilm formed of, for example, aluminum or silver (Ag) is used as thematerial of the reflection film.

The plurality of organic electroluminescent light-emitting elements 30are formed on the planarization film 13 via, for example, the reflectionfilm 31. The plurality of organic electroluminescent light-emittingelements 30 are provided in a matrix according to the pixels P in anarea corresponding to the display area D above the flexible substrate 5.

The organic electroluminescent light-emitting element 30 includes ananode 32, an organic layer 33 including at least a light-emitting layer,and a cathode 34 formed so as to cover the organic layer 33, therebyfunctioning as a light-emitting source.

The anode 32 is an electrode to inject a drive current into the organiclayer 33. The anode 32 is connected to the contact hole 32 a and thuselectrically connected to the thin film transistor 11, so that a drivecurrent is supplied from the thin film transistor 11.

The anode 32 is formed of a conductive material. Specifically, forexample, the material of the anode 32 is preferably ITO (Indium TinOxide), but may be a light-transmissive and conductive material such asIZO (indium-zinc composite oxide), tin oxide, zinc oxide, indium oxide,or aluminum oxide composite oxide. When the reflection film 31 is formedof metal such as silver and in contact with the anode 32, the reflectionfilm functions as a portion of the anode 32.

A pixel separation film 14 is formed along each border between thepixels P adjacent to each other between the anodes 32 adjacent to eachother. The pixel separation film 14 has functions of preventing contactbetween the anodes 32 adjacent to each other and leakage current betweenthe anode 32 and the cathode 34. The pixel separation film 14 is formedof an insulating material. Specifically, for example, the pixelseparation film 14 is formed of a photosensitive resin composition.

The organic layer 33 is a layer formed of an organic material andincluding at least a light-emitting layer, and is formed so as to coverthe anode 32. The organic layer 33 is not limited to the configurationin which the organic layer is formed for each of the anodes 32, but maybe formed so as to cover the entire surface of an area where the pixelsP are arranged in the display area D. The organic layer 33 includes alight-emitting layer that emits light. The emitted light may be white orhave other colors.

The organic layer 33 includes, for example, a hole injection layer, ahole transport layer, a light-emitting layer, an electron transportlayer, and an electron injection layer (all not shown) stacked in thisorder from the anode 32 side. The stacked structure of the organic layer33 is not limited to that described herein, and the stacked structure isnot specified as long as the stacked structure includes at least alight-emitting layer.

The light-emitting layer is composed of, for example, an organicelectroluminescent substance that emits light in response to thecombination of holes and electrons. As such an organicelectroluminescent substance, for example, a substance used generally asan organic light-emitting material may be used.

The cathode 34 is formed so as to cover the organic layer 33. Thecathode 34 is not limited to the configuration in which the cathode isformed in each of the pixels P, but may be formed so as to cover theentire surface of the area where the pixels P are arranged in thedisplay area D. With the configuration described above, the cathode 34is in common contact with the organic layers 33 of the plurality oforganic electroluminescent light-emitting elements 30.

The cathode 34 is formed of a light-transmissive and conductivematerial. Specifically, for example, the material of the cathode 34 ispreferably ITO, but may be a material obtained by mixing metal such assilver or magnesium into a conductive metal oxide such as ITO or InZnO,or by stacking a metal thin film such as of silver or magnesium and aconductive metal oxide on each other.

The organic electroluminescent light-emitting elements 30 (the cathode34) are covered with the sealing film 40 over the plurality of pixels P.The sealing film 40 is a transparent film formed of an insulatingmaterial that covers the entire first substrate 10 to thereby preventthe penetration of oxygen or moisture into the layers including theorganic layer 33.

The upper surface of the first substrate 10 (an upper surface 40 a ofthe sealing film 40) is covered with the second substrate 50 via afiller 45 formed of, for example, an inorganic material. The secondsubstrate 50 is, for example, a substrate having a perimeter smallerthan that of the first substrate 10 in a plan view, and is arranged soas to face the display area D of the first substrate 10. Specifically,for example, a color filter substrate can be used as the secondsubstrate 50 when the light-emitting layer of the organic layer 33 emitswhite light. With the use of a color filter substrate as the secondsubstrate 50, the display device 1 can perform color display.

Next, with reference to FIGS. 1 and 3, the IC chip 3 arranged on thenon-display area E of the first substrate 10 and the surroundingconfiguration of the IC chip 3 will be described in detail. FIG. 3 is aschematic cross-sectional view of the display device 1 shown in FIG. 1along the cut line III-III.

The IC chip 3 is an IC (Integrated Circuit) that is arranged on thefirst substrate 10 and supplied with image data from the outside of thedisplay device 1 via an external apparatus (not shown). As shown in FIG.1, the IC chip 3 is provided in an area where the second substrate 50 isnot arranged on the upper surface 10 a of the first substrate 10.Moreover, the IC chip 3 is connected to the thin film transistors 11 inthe display area D through first wirings 20 formed in the non-displayarea E.

As shown in FIG. 3, the IC chip 3 includes terminals 73 connected to thefirst substrate 10. The terminal 73 is formed of, for example, metal,and pressure bonded via an anisotropic conductive film 72 to a terminalelectrode 71 formed on the upper surface 10 a of the first substrate 10.

In the anisotropic conductive film 72, conductive particles (not shown)are contained. Since pressure to the first substrate 10 side is appliedfrom the terminal 73 of the IC chip 3 to the anisotropic conductive film72, a conductive path is formed on surfaces of the conductive particlesto provide electrical conduction between the terminal 73 and theterminal electrode 71.

Next, the configuration of an area of the first substrate 10corresponding to the area where the IC chip 3 is arranged will bedescribed in detail. As shown in FIG. 3, the area of the first substrate10 includes: for example, the flexible substrate 5; the undercoat layer6, an insulating support layer 61 a, a first insulating film 61 b, ametal support layer 61 c, a second insulating film 61 d, second wirings61 e, and a third insulating film 61 f that are stacked in this order onthe flexible substrate 5; and the terminal electrodes 71. Theconfigurations of the flexible substrate 5 and the undercoat layer 6 arethe same as those of the first substrate 10 in the display area D.Therefore, the configurations of the insulating support layer 61 a tothe terminal electrode 71 will be described in detail below.

The insulating support layer 61 a is a support layer whose hardness ishigher than that of the flexible substrate 5, for preventing the stressof the IC chip 3 from acting on the first substrate 10 around the ICchip 3 and suppressing the absorption of the pressure acting from the ICchip 3 on the first substrate 10 by the flexible substrate 5.

As shown in FIGS. 1 and 3, the plan view shape of the insulating supportlayer 61 a is larger than that of the IC chip 3. When the perimeter ofthe insulating support layer 61 a is defined as a perimeter 61 a ₁, theperimeter 61 a ₁ is located on the outside of a perimeter 3 a of the ICchip 3 in the plan view. The insulating support layer 61 a is formed soas to cover at least an area of an upper surface of the undercoat layer6, the area corresponding to the area where the IC chip 3 is arranged.

Specifically, for example, the insulating support layer 61 a is formedof an insulating material such as polysilicon. The material of theinsulating support layer 61 a is not limited to polysilicon. The supportlayer 61 a may be formed of other materials than polysilicon as long asthe hardness of the support layer 61 a is greater than that of theflexible substrate 5.

The insulating support layer 61 a in the non-display area E shown inFIG. 3 is formed in the same layer as, for example, the polysiliconsemiconductor layer 11 a in the display area D shown in FIG. 2. Theforming place of the insulating support layer 61 a is not limited to thesame layer as the polysilicon semiconductor layer 11 a. The insulatingsupport layer 61 a may be formed on other layers as long as theinsulating support layer 61 a is located between the flexible substrate5 and the anisotropic conductive film 72.

Moreover, the insulating support layer 61 a is preferably locatedoutside the display area D in the plan view. As shown in FIG. 1, theinsulating support layer 61 a is specifically arranged in an area wherethe second substrate 50 is not arranged, in an area of the upper surface10 a of the first substrate 10, the area corresponding to thenon-display area E in the plan view.

The insulating support layer 61 a and an area of the undercoat layer 6exposed from the insulating support layer 61 a are covered with thefirst insulating film 61 b. The first insulating film 61 b is formed of,for example, the same material as that of the gate insulating layer 11 bin the display area D, and formed in the same layer as the gateinsulating layer 11 b.

The metal support layer 61 c is a support layer whose hardness is higherthan that of the flexible substrate 5, for preventing the stress of theIC chip 3 from acting on the first substrate 10 around the IC chip 3 andsuppressing the absorption of the pressure acting from the IC chip 3 onthe first substrate 10 by the flexible substrate 5. The metal supportlayer 61 c is formed so as to cover at least an area of an upper surfaceof the first insulating film 61 b, the area corresponding to the areawhere the IC chip 3 is arranged. As shown in FIGS. 1 and 3, the planview shape of the metal support layer 61 c is larger than that of the ICchip 3, and a perimeter 61 c ₁ of the metal support layer 61 c islocated on the outside of the perimeter 3 a of the IC chip 3.

As shown in FIG. 1, the metal support layer 61 c is located outside thedisplay area D in the plan view. As shown in FIGS. 2 and 3, the metalsupport layer 61 c is formed in, for example, the same layer as the gateelectrode (wiring) 11 c in the display area D. The metal support layer61 c is formed of, for example, MoW, which is the same material as thatof the gate electrode 11 c. The metal support layer 61 c may be formedof other materials as long as the hardness of the metal support layer 61c is higher than that of the flexible substrate 5. The forming place ofthe metal support layer 61 c is not limited to the same layer as thegate electrode 11 c. The metal support layer 61 c may be formed on otherlayers as long as the metal support layer 61 c is located between theflexible substrate 5 and the anisotropic conductive film 72.

The metal support layer 61 c and an area of the first insulating film 61b exposed from the metal support layer 61 c are covered with the secondinsulating film 61 d. The second insulating film 61 d is formed of, forexample, the same material as that of the second insulating film 11 d inthe display area D. The second insulating film 61 d is formed in thesame layer as the second insulating film 11 d.

The second wirings 61 e formed of, for example, aluminum are formed onthe second insulating film 61 d. The second wiring 61 e is a wiring totransmit a video signal from the IC chip 3 to the source-drain electrode11 e in the display area D. The second wiring 61 e is formed of, forexample, the same material as that of the source-drain electrode 11 e inthe display area D. The second wiring 61 e is formed in the same layeras the source-drain electrode 11 e.

The second wirings 61 e and an area of the second insulating film 61 dexposed from the second wirings 61 e are covered with the thirdinsulating film 61 f. The third insulating film 61 f is formed of, forexample, the same material as that of the third insulating film 11 f inthe display area D. The third insulating film 61 f is formed in the samelayer as the third insulating film 11 f.

The terminal electrodes 71 each of which connects the IC chip 3 with thesecond wiring 61 e via the anisotropic conductive film 72 are formed onthe third insulating film 61 f. The terminal electrode 71 is connectedto the second wiring 61 e via a contact hole 71 a penetrating the thirdinsulating film 61 f. The terminal electrode 71 is formed of, forexample, a light-transmissive material such as ITO. The terminalelectrode 71 is formed in the same layer as the anode 32 in the displayarea D. Since the terminal electrode 71 is electrically conducted to theterminal 73 of the IC chip 3, the IC chip 3 and the thin filmtransistors 11 in the display area D are electrically connected witheach other.

In the display device 1 in the embodiment, the support layer (at leastone of the insulating support layer 61 a and the metal support layer 61c) whose plan view shape is larger than that of the IC chip 3 and whosehardness is higher than that of the flexible substrate 5 is formedbetween the anisotropic conductive film 72 and the flexible substrate 5.Due to this, the absorption of the pressure acting from the IC chip 3 onthe anisotropic conductive film 72 by the flexible substrate 5 issuppressed, compared with a display device not including the supportlayer.

For this reason, compared with a display device not having theconfiguration, the display device 1 in the embodiment can realize thestabilization of electrical conduction between the IC chip 3 and thethin film transistors 11 via the anisotropic conductive film 72. Due tothis, an improvement in the reliability of the display device 1 can berealized.

Moreover, in the display device 1 in the embodiment, since the supportlayer is formed, the stress of the IC chip 3 caused by a temperaturechange is prevented from acting on the first substrate 10 around the ICchip 3, compared with a display device not having the configuration. Forthis reason, deformation such as crinkles is prevented from occurring inthe surface of the first substrate 10 around the IC chip 3, so that animprovement in the reliability of the display device 1 can be realized.

Moreover, in the display device 1 in the embodiment, since theinsulating support layer 61 a is located outside the display area D inthe plan view, it is possible to adopt a configuration in which theinsulating support layer 61 a is formed in the same layer as the gateinsulating layer 11 b in the display area D. For this reason, thedisplay device 1 in the embodiment can obtain the above-describedadvantageous effects of the invention without increasing the thicknessof the first substrate 10 in the display area D, compared with a displaydevice not having the configuration.

Similarly, in the display device 1 in the embodiment, since the metalsupport layer 61 c is located outside the display area D in the planview, it is possible to adopt a configuration in which the metal supportlayer 61 c is formed in the same layer as the gate electrode 11 c in thedisplay area D. For this reason, it is possible to obtain theabove-described advantageous effects of the invention without increasingthe thickness of the first substrate 10 in the display area D, comparedwith a display device not having the configuration.

Moreover, in the display device 1 in the embodiment, since the metalsupport layer 61 c formed of metal is formed between the anisotropicconductive film 72 and the flexible substrate 5, the absorption of thepressure acting from the IC chip 3 on the anisotropic conductive film 72by the flexible substrate 5 is suppressed, compared with a displaydevice in which only the insulating support layer 61 a is formed. Forthis reason, the display device 1 in the embodiment can realize animprovement in reliability.

Moreover, in the display device 1 in the embodiment, since the metalsupport layer 61 c is formed in the area corresponding to the IC chip 3,the stress of the IC chip 3 is further prevented from acting on thefirst substrate 10 around the IC chip 3, compared with a display devicein which only the insulating support layer 61 a is formed. For thisreason, the display device 1 in the embodiment can realize animprovement in reliability.

Moreover, in the display device 1 in the embodiment, since at least oneof the support layers is the insulating support layer 61 a formed of aninsulating material, insulation between the terminal electrode 71 andthe flexible substrate 5 is enhanced, compared with a display device nothaving the configuration. Due to this, the display device 1 in theembodiment can realize an improvement in reliability.

The display device 1 according to the embodiment has been described sofar, but the configuration of the display device 1 is not limited to theembodiment described above. FIG. 4 is a schematic cross-sectional viewshowing a modified example of the display device 1 shown in FIG. 1 inthe same view as FIG. 3. It is preferable that both the insulatingsupport layer 61 a and the metal support layer 61 c are formed. However,as shown in FIG. 4 for example, it is sufficient that only one of themis formed.

When only the insulating support layer 61 a is formed as a support layeras shown in the drawing, wiring lower portions 62 c formed of the samematerial as that of the gate electrode 11 c in the display area D may beformed in the same layer as the gate electrode 11 c. When the displaydevice 1 has the configuration described above, the wiring lower portion62 c is connected with the second wiring 61 e and functions as a portionof the second wiring 61 e.

In the display device 1, since only the insulating support layer 61 aformed of an insulating material is formed as a support layer asdescribed above, a short circuit between the terminal electrode 71 andthe support layer is prevented, compared with a display device nothaving the configuration. Due to this, the display device 1 in themodified example can realize an improvement in reliability.

Moreover, the number of support layers is not limited to two. Three ormore support layers may overlap as long as the hardness of the supportlayers is higher than that of the flexible substrate 5, the supportlayers are formed between the flexible substrate 5 and the anisotropicconductive film 72, and the plan view shape of the support layers islarger than that of the IC chip 3.

Next, a method of manufacturing the display device 1 according to anembodiment of the invention will be described with reference to thedrawings. The method of manufacturing the display device 1 in theembodiment includes a step of forming the flexible substrate on a basicsubstrate 70, a step of forming one or more support layers on theflexible substrate 5 in the non-display area E, a step of forming thethin film transistors 11 and the organic electroluminescentlight-emitting elements 30 on the flexible substrate 5 in the displayarea D, a step of arranging the counter substrate 50 on the display areaD, a step of pressure bonding the IC chip 3 in the non-display area E,and a step of separating the flexible substrate 5 from the basicsubstrate 70.

FIG. 5 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. First, the flexible substrate 5 that is formed of, forexample, polyimide and segmented into the display area D and thenon-display area E outside the display area D is formed on the basicsubstrate 70. The basic substrate 70 is a substrate used as the base ofthe flexible substrate 5, for which, for example, a glass substrate isused. The basic substrate 70 is not limited to a glass substrate, and asubstrate formed of other materials may be used as long as the substratehas strength enough to function as the base of the flexible substrate 5.Next, the undercoat layer 6 formed of an insulating material is stackedon the flexible substrate 5.

FIG. 6 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. Next, a layer formed of, for example, an insulating materialsuch as polysilicon is formed so as to cover an upper surface of theundercoat layer 6 in the non-display area E. In this case, a layerformed of an insulating material may be formed, not only in thenon-display area E, but also similarly in the display area D. Theinsulating material is not limited to polysilicon, and other materialsmay be used as long as the hardness is higher than that of the flexiblesubstrate 5.

Next, the layer formed of an insulating material is patterned to formthe insulating support layer 61 a as a support layer whose hardness ishigher than that of the flexible substrate 5 in the non-display area E.In the patterning, as shown in FIGS. 1 and 6, the forming range of theinsulating support layer 61 a is adjusted such that the insulatingsupport layer 61 a is located outside the display area D in the planview.

In the step of patterning the insulating support layer 61 a, thepolysilicon semiconductor layer 11 a shown in FIG. 2 may be formed inthe display area D in the same layer as the insulating support layer 61a in the non-display area E by simultaneously patterning the layerformed of an insulating material also in the display area D.

FIG. 7 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. Next, the first insulating film 61 b formed of an insulatingmaterial is formed so as to cover the insulating support layer 61 a andthe undercoat layer 6 exposed from the insulating support layer 61 a. Inthe step, the gate insulating layer 11 b formed of the same material asthat of the first insulating film 61 b may be formed also on theundercoat layer 6 in the display area D shown in FIG. 2.

Next, a metal film such as of, for example, MoW is formed so as to coverthe first insulating film 61 b in the non-display area E. In the step, ametal film may be formed also on the gate insulating layer 11 b in thedisplay area D shown in FIG. 2. The material of the metal film is notlimited to MoW, and other materials may be used as long as the hardnessof the material is higher than that of the flexible substrate 5.

FIG. 8 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. Next, the metal film formed on the first insulating film 61 bis patterned to form the metal support layer 61 c as a support layerwhose hardness is higher than that of the flexible substrate 5 in thenon-display area E. In the patterning, as shown in FIGS. 1 and 8, theforming range of the metal support layer 61 c is adjusted such that themetal support layer 61 c is located outside the display area D in theplan view.

In the step of forming the metal support layer 61 c, the gate electrode(wiring) 11 c shown in FIG. 2 may be formed in the same layer as themetal support layer 61 c in the display area D by simultaneouslypatterning the metal film also in the display area D.

Next, the second insulating film 61 d formed of an insulating materialis formed so as to cover the metal support layer 61 c and the firstinsulating film 61 b exposed from the metal support layer 61 c. In thiscase, the second insulating film. 11 d in the same layer as the secondinsulating film 61 d in the non-display area E may be formed in thedisplay area D by forming an insulating material so as to cover the gateelectrode (wiring) 11 c also in the display area D.

Next, an aluminum film, for example, is deposited so as to cover thesecond insulating film 61 d. FIG. 9 is a schematic cross-sectional viewshowing the display device 1 shown in FIG. 1 in the same view as FIG. 3,showing the method of manufacturing the display device 1 according tothe embodiment of the invention. Next, the aluminum film is patterned tothereby form the second wirings 61 e in an area corresponding to theinsulating support layer 61 a and the metal support layer 61 c. Thematerial of the second wiring 61 e is not limited to aluminum, and othermaterials may be used.

Moreover, in the step, the source-drain electrode 11 e formed of thesame material as that of the second wiring 61 e may be formed bypatterning an aluminum film also in the same layer as the second wiring61 e in the display area D.

FIG. 10 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. Next, the third insulating film 61 f formed of an insulatingmaterial is formed so as to cover the second wirings 61 e and exposedareas of the second insulating film 61 d.

In the step of forming the third insulating film 61 f, the thirdinsulating film 11 f in the same layer as the third insulating film 61 fin the non-display area E may be formed by similarly stacking aninsulating material also in the display area D. Due to this, the thinfilm transistor 11 shown in FIG. 2 is formed on the display area D ofthe flexible substrate 5.

Next, as shown in FIG. 10, the contact holes 71 a through each of whichan upper surface 61 e ₁ of the second wiring 61 e is exposed is formedto penetrate the third insulating film 61 f in the non-display area E.

FIG. 11 is a schematic cross-sectional view showing the display device 1shown in FIG. 1 in the same view as FIG. 3, showing the method ofmanufacturing the display device 1 according to the embodiment of theinvention. Next, a light-transmitting film formed of alight-transmissive material such as ITO is coated so as to cover anupper surface of the third insulating film 61 f and the insides of thecontact holes 71 a. Next, the light-transmitting film is patterned tothereby form the terminal electrodes 71 covering the insides of thecontact holes 71 a.

In the step of forming the terminal electrode 71, the anode 32 may beformed by similarly forming and patterning a light-transmitting filmalso in the display area D.

Thereafter, as shown in FIG. 2, by forming the pixel separation films14, the organic electroluminescent light-emitting elements 30, and thesealing film 40 on the display area D of the flexible substrate 5, thefirst substrate 10 including the flexible substrate 5, the undercoatlayer 6, the circuit layer 12 including the thin film transistors 11,the planarization film 13, the organic electroluminescent light-emittingelements 30, and the sealing film 40 is formed.

Next, the second substrate (counter substrate) 50 is arranged so as toface an upper surface of the display area D of the first substrate 10via the filler 45.

Next, as shown in FIGS. 1 and 3, the IC chip 3 whose plan view shape issmaller than those of the support layers is pressure bonded on thenon-display area E of the support layers (the insulating support layer61 a and the metal support layer 61 c) via the anisotropic conductivefilm 72 so as to be located on the inside of the support layers in theplan view.

Specifically, the anisotropic conductive film 72 is first attached onthe terminal electrodes 71. Next, the IC chip 3 including the terminals73 is arranged such that the terminal 73 is located on the terminalelectrode 71 via the anisotropic conductive film 72. Next, by applyingpressure from above the IC chip 3 while heating, the terminals 73 of theIC chip 3 are pressure bonded to the terminal electrodes 71 via theanisotropic conductive film 72. Due to this, the IC chip 3 and the thinfilm transistors 11 in the display area D are electrically conducted toeach other.

Thereafter, by separating the flexible substrate 5 from the basicsubstrate 70, the display device 1 shown in FIGS. 1 to 3 is formed.

In the method of manufacturing the display device 1 in the embodiment,at least one of the insulating support layer 61 a and the metal supportlayer 61 c is formed, between the anisotropic conductive film 72 and theflexible substrate 5, as a support layer whose plan view shape is largerthan that of the IC chip 3 and whose hardness is higher than that of theflexible substrate 5. Therefore, compared with a method of manufacturinga display device not having the configuration, the absorption of thepressure acting on the anisotropic conductive film 72 when pressurebonding the IC chip 3 by the flexible substrate 5 is suppressed. Forthis reason, the IC chip 3 and the thin film transistor 11 can beelectrically conducted stably to each other. Due to this, the displaydevice 1 with high reliability can be manufactured.

Moreover, in the method of manufacturing the display device 1 in theembodiment, since the insulating support layer 61 a, for example, isformed as a support layer, stress caused by heating and cooling whenpressure bonding the IC chip 3 is prevented from acting on the firstsubstrate 10 around the IC chip 3, compared with a method ofmanufacturing a display device not having the configuration. For thisreason, the IC chip 3 and the first substrate 10 can be bonded to eachother without the occurrence of deformation in the surface of the firstsubstrate 10 around the IC chip 3.

Moreover, in the method of manufacturing the display device 1 in theembodiment, since the insulating support layer 61 a formed of aninsulating material is formed as a support layer, insulation between theterminal electrode 71 and the flexible substrate 5 can be enhancedcompared with a method of manufacturing a display device not having theconfiguration, so that the display device 1 with high reliability can bemanufactured.

Moreover, in the method of manufacturing the display device 1 in theembodiment, since the support layer is formed so as to be locatedoutside the display area D in the plan view, the insulating supportlayer 61 a can be formed in the same layer as the gate insulating layer11 b in the display area D. For this reason, the above-describedadvantageous effects of the invention can be obtained without increasingthe thickness of the first substrate 10 in the display area D, comparedwith a method of manufacturing a display device not having theconfiguration.

Moreover, in the method of manufacturing the display device 1 in theembodiment, since the metal support layer 61 c formed of metal is formedas one of the support layers between the anisotropic conductive film 72and the flexible substrate 5, the absorption of the pressure acting fromthe IC chip 3 on the anisotropic conductive film 72 by the flexiblesubstrate 5 is suppressed, compared with a display device not having theconfiguration. For this reason, an improvement in the reliability of thedisplay device 1 can be realized.

Moreover, since the metal support layer 61 c is formed in the same layeras the gate electrode (wiring) 11 c of the thin film transistor 11 inthe display area D, the above-described advantageous effects of theinvention can be obtained without increasing the thickness of the firstsubstrate 10 in the display area D, compared with a method ofmanufacturing a display device not having the configuration.

Moreover, in the method of manufacturing the display device 1 in theembodiment, since both the insulating support layer 61 a and the metalsupport layer 61 c are formed as support layers, the occurrence ofdeformation in the surface of the first substrate 10 when pressurebonding the IC chip 3 and a failure of electrical conduction between theIC chip 3 and the thin film transistor 11 can be suppressed, comparedwith a manufacturing method in which only any one of the support layersis formed.

The embodiments of the invention have been described so far, but theinvention is not limited to the embodiments described above. Forexample, the configurations described in the embodiments described abovemay be replaced with substantially the same configuration, aconfiguration providing the same operational effect, or a configurationcapable of achieving the same object.

FIG. 12 is a schematic cross-sectional view showing the display device 1shown in FIG. 4 in the same view as FIG. 3, showing a modified exampleof the method of manufacturing the display device according to theembodiment of the invention. For example, as shown in the drawing, thewiring lower portions 62 c may be formed, instead of the metal supportlayer 61 c, in the same layer as the gate electrode 11 c in the displayarea D. Since only the insulating support layer 61 a is formed as asupport layer as described above, it is possible to manufacture thedisplay device 1 with high reliability that can prevent a short circuitbetween the terminal electrode 71 and the support layer, compared with amethod of manufacturing a display device not having the configuration.

The number of support layers to be formed is not limited to two. Threeor more support layers may be formed as long as the hardness is higherthan that of the flexible substrate 5, the plan view shape is largerthan that of the IC chip 3, and the support layers are formed betweenthe flexible substrate 5 and the anisotropic conductive film 72.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaim cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: a first substratethat includes a flexible substrate, which is segmented into a displayarea and a non-display area outside the display area, and includes athin film transistor and a display element formed on the display area ofthe flexible substrate; a metal support layer over the flexiblesubstrate in the non-display area without extending to the display areaand without directly contacting any electrodes, the metal support layerbeing harder than the flexible substrate; a first insulating filmbetween the metal support layer and the flexible substrate; a secondinsulating film with the metal support layer interposed between thefirst insulating film and the second insulating film; a second substratethat is arranged so as to face an upper surface of the display area ofthe first substrate; and an IC chip that is mounted on the firstsubstrate, the IC chip entirely overlapping with an area where the metalsupport layer is continuously provided in a plan view, wherein, the thinfilm transistor has a gate electrode, source and drain electrodes, and apolysilicon semiconductor layer, the first insulating film and thesecond insulating film extend to the non-display area with the gateelectrode interposed between the first insulating film and the secondinsulating film, the metal support layer lies between the flexiblesubstrate and the IC chip, and the metal support layer is larger thanthe IC chip to encompass the IC chip in a plan view, and the metalsupport layer is formed in the same layer as a wiring of the thin filmtransistor.
 2. The display device according to claim 1, furthercomprising another insulating film formed in the non-display area andcloser to a side of the flexible substrate than the metal support layer.3. The display device according to claim 1, wherein the first insulatingfilm is formed on a polysilicon layer in the non-display area.
 4. Thedisplay device according to claim 1, wherein the first insulating filmis formed in the non-display area in the same layer as a gate insulatingfilm of the thin film transistor.
 5. The display device according toclaim 1, wherein the polysilicon semiconductor layer lies between thefirst insulating film and the flexible substrate.
 6. A method ofmanufacturing a display device comprising the steps of: forming, on abasic substrate, a flexible substrate that is segmented into a displayarea and a non-display area outside the display area; forming a firstinsulating film over the flexible substrate; forming, over the firstinsulating film, in the non-display area without extending to thedisplay area and without directly contacting any electrodes, a metalsupport layer whose hardness is higher than that of the flexiblesubstrate; forming a gate electrode of a thin film transistor over thefirst insulating film in the display area; forming a second insulatingfilm over the metal support layer and the gate electrode; forming, onthe display area of the flexible substrate, a display element; arranginga counter substrate so as to face the display area; bonding, on thenon-display area of the metal support layer, an IC chip whose plan viewshape is smaller than that of the metal support layer so as to belocated to entirely overlap with an area where the metal support layeris continuously provided in a plan view; and separating the flexiblesubstrate from the basic substrate, wherein the metal support layer isinterposed between the first insulating film and the second insulatingfilm, the gate electrode is interposed between the first insulating filmand the second insulating film, and the metal support layer is formed inthe same layer as a wiring of the thin film transistor.
 7. The method ofmanufacturing a display device according to claim 6, further comprisingforming the first insulating film on a polysilicon layer in thenon-display area before forming the metal support layer.
 8. The methodof manufacturing a display device according to claim 6, furthercomprising forming a polysilicon semiconductor layer of the thin filmtransistor before forming the first insulating film and the gateelectrode, wherein the first insulating film is interposed between thepolysilicon semiconductor layer and the gate electrode.